NEWARK, N.J. — The New York Giants aren’t the only winners in the team’s upset victory over the New England Patriots in the Super Bowl.

Hats, T-shirts and other gear bearing the Giants logo started flying off the racks at sporting goods stores around the New York area right after the game ended, and the NFL estimated Monday that the total sales of official Super Bowl merchandise could surpass the $125 million record set more than a decade ago.

But with fans lining up to buy Giants-branded memorabilia, Boston merchants may be wondering what to do with their “19-0” hats and T-shirts.

Reebok, the NFL’s official apparel provider, printed 300 hats and T-shirts for both teams as it normally does, according to league spokesman Brian McCarthy. But with the lead changing hands three times in the final quarter, the boxes containing the gear sat just off the field, waiting to be distributed after the final whistle, he said.

In New York, New England and Phoenix, screen printers for the league’s licensees were poised to start churning out products. It wasn’t clear how many jumped the gun and started printing Patriots championship gear.

“We tell them not to begin preproduction, but it’s at their own risk,” McCarthy said. “We don’t want to have a ’Dewey Beats Truman’ situation,” he added, referring to the Chicago Tribune’s infamous headline trumpeting the wrong winner in the 1948 presidential race.

For Giants fans, the buying frenzy began not long after wide receiver Plaxico Burress hauled in the game-winning touchdown pass from Eli Manning with 35 seconds left.

At a Sports Authority in Clifton, a few miles west of Giants Stadium in East Rutherford, fans bought up 1,000 items immediately after the game, then snapped up about 1,500 more by mid-afternoon Monday, according to co-manager Angelo Rizzo.

In Princeton, Dick’s Sporting Goods reopened shortly after the game ended Sunday night. Five customers were already at the door, manager Dan Fisher said.

Fisher said he had been home watching the game and consulting with employees by phone about whether to put out the Super Bowl items.

“Because it was going down to the wire, it was like, ’Do you set it up or not?”’ Fisher said. “It was quite a surprise to see New England lose.”

At least one New England retailer took a cautious route. City Sports Inc., a Wilmington, Mass.-based chain with seven of its 14 stores in the Boston area, stuck with its policy of ordering a team’s shirts and hats only if that team ends up winning a big game.

“Going into the game, with a chance to be 19-0 on the line, it was a big letdown,” said Michael Lewis, the chain’s equipment and license buyer. “That’s the kind of vibe we’re getting today not only from our stores, but here in our corporate offices as well. We’re fans, too.”

Judging by sales at the game site and the size of the New York market, McCarthy said the league expected this year’s haul to surpass the record sales set in 1997, when Green Bay beat the Patriots in Super Bowl XXXI.

Each NFL team receives an equal share of the revenue from official Super Bowl merchandise sales, McCarthy said.

Children far removed from the game benefit as well, thanks to a partnership developed in 1994 between the NFL and the relief organization World Vision. By next week, World Vision will have delivered the pre-printed — and incorrect — Patriots champion gear to underprivileged children in Nicaragua.

Last year, the league donated Chicago Bears merchandise to children in Zambia after the Bears lost to the Indianapolis Colts, according to World Vision spokeswoman Anne Duffy.

Closer to home, Giants fans reveled in the opportunity to show their colors.

Fred Siegel, 68, a Giants fan from Marlboro who works in New York, tried on T-shirts at the Modell’s store in Herald Square.

“It’s like something that I may never see again in my lifetime,” Siegel said. “The Giants played great, the defense was fabulous, Manning finally came of age; you can’t ask for anything else.”

Even in southern New Jersey, where most fans support Philadelphia teams, Giants fans were coming out of the woodwork — and into the mall.

Betsy Atkinson, 49, from the Philadelphia suburb of Cinnaminson, bought a Giants T-shirt as a birthday gift for her husband.

“I was hoping they’d lose so the stuff would be half off,” she joked.

But few shoppers seemed interested in buying discounted Patriots gear celebrating the team’s AFC title at a City Sports store in downtown Boston.

Abraham Ho, a 19-year-old Suffolk University student from Quincy, had been counting on a Patriots victory to justify his plans to buy replica jerseys. After their loss, Ho couldn’t get enthused about spending the money.

“I was real disappointed,” said Ho. “But if I see a Patriots hat design that I like, I’ll still probably get it.”